This application is based upon, claims the benefit of priority of, and incorporates by reference, the contents of Japanese Patent Application No. 2002-134152 filed May 9, 2002.
1. Field of the Invention
The present invention relates to a vehicle air-conditioning system that drives a compressor for a refrigerating cycle with an electric motor.
2. Description of the Related Art
Generally, in an air-conditioning system, the number of revolutions of the electric motor is controlled to control the amount of refrigerant discharged by the compressor in order to adjust the cooling capability. Electric power consumed by the air-conditioning system is limited based on the air conditioning load for the purpose of saving power (see Japanese Patent Laid-Open Publication No. Hei 11-34649).
In this conventional system, however, when the power consumption by the air-conditioning system is limited and a defroster mode or a foot defroster mode is selected, window fogging cannot be cleared quickly enough in some cases. More specifically, the limit on the power consumption prevents the electric motor and compressor from operating at a high number of revolutions, which causes the dehumidifying and cooling capability to be inadequate, and window fogging cannot be cleared quickly enough.
The present invention is directed to a solution to the above disadvantage. It is an object of the invention to provide a vehicle air-conditioning system that drives a compressor with an electric motor and is capable of quickly removing fog (moisture) from the window(s) when a defogging blowing mode to blow air to the glass window(s) is selected.
A vehicle air-conditioning system according to a first aspect of the present invention includes a compressor (23) that compresses a refrigerant and discharges the compressed refrigerant, an electric motor (22) that drives the compressor (23), and a heat exchanger (21) that uses the refrigerant for cooling air blown into a vehicle compartment of a vehicle. Electric power used by the electric motor (22) is limited in a prescribed condition. In the system, the limit on the electric power used by the electric motor (22) is lifted when a defogging blowing mode to blow air at the glass windows is selected.
In this way, when the defogging blowing mode is selected, the function of securing the field of view has priority over the power saving function. Therefore, the number of revolutions of the compressor is increased to raise the dehumidifying and cooling capability, so that the fog can quickly be removed from the window.
According to a second aspect of the invention, when the defogging blowing mode is selected, the number of revolutions of the compressor (23) is increased to a target number of revolutions and then held at the target number of revolutions for a prescribed period. In this way, since the number of revolutions of the compressor is held at the target number of revolutions for the prescribed period, the humidifying and cooling capability can be kept at a high level for the period, so that the fog can be removed from the windows even more quickly.
According to a third aspect of the invention, when the defogging blowing mode is selected, the number of revolutions of the compressor (23) is increased to the target number of revolutions at a maximum increasing speed for the number of revolutions. In this way, since the number of revolutions of the compressor is increased to the target number of revolutions at a maximum increasing speed, the humidifying and cooling capability can quickly be raised to a higher level, so that the fog can be removed from the window even more quickly.
According to a fourth aspect of the invention, the prescribed period can be determined based on at least one of the temperature of the outside air, the temperature of the glass windows, and humidity in the vehicle compartment. According to a fifth aspect of the invention, the target number of revolutions is determined based on at least one of the temperature of the outside air, the temperature of the glass windows, and humidity in the vehicle compartment.
A vehicle air-conditioning system according to a sixth aspect of the invention is for use in a hybrid vehicle that includes an engine (1) that generates driving force for driving the vehicle, a generator (2) driven by the engine (1) to generate electricity, a battery (4) charged by the electricity generated by the generator (2), and a driving electric motor (2) fed by the battery (4) to generate driving force for vehicle driving. The air-conditioning system includes a compressor (23) that compresses a refrigerant and discharges the compressed refrigerant, an electric motor (22) for the compressor fed by the battery (4) to drive the compressor (23), and a heat exchanger (21) for cooling air, blown into a vehicular compartment, with the refrigerant. Electric power used by the electric motor (22) for the compressor is limited in a prescribed condition. The limit on the electric power used by the electric motor (22) for the compressor is disregarded when a defogging blowing mode to blow air to the glass windows is selected. In this way, in the vehicle air-conditioning system having an engine and an electric motor for driving, the same effect as in the first aspect can be provided.
According to a seventh aspect of the invention, when the defogging blowing mode is selected, the number of revolutions of the compressor (23) is increased to a target number of revolutions and then kept at the target number of revolutions for a prescribed period. In this way, in the air-conditioning system in the hybrid vehicle having an engine and an electric motor for driving, the same effect as in the second aspect can be provided.
According to an eighth aspect of the invention, when the defogging blowing mode is selected, the number of revolutions of the compressor (23) is increased to the target number of revolutions at a maximum increasing speed for the number of revolution.
In this way, in the air-conditioning system in the hybrid vehicle having an engine and an electric motor for driving, the effect the same as that by the third aspect can be provided.
According to a ninth aspect of the invention, the target number of revolutions is set to a higher level while the engine (1) is operated than while the engine is stopped. Additionally, in the hybrid vehicle, the engine is stopped when the automobile is stopped or when the automobile is driven at a low speed with a low load. Therefore, when the engine is stopped and there is no engine operation noise, the compressor is operated at a relatively low speed so that the operation noise of the compressor is less annoying. Meanwhile, when the engine is operated, the operation noise caused by the high speed operation of the compressor is masked by the engine operation noise. Therefore, when the compressor is operated at a relatively high speed, the operation noise of the compressor is less annoying.
In a hybrid vehicle, when the remaining capacity of the battery is small for example, the engine begins to drive the generator to charge the battery. When the number of revolutions of the compressor is increased, the remaining capacity of the battery is reduced by the power consumption increase, which is more likely to cause starting of the engine to charge the battery. Therefore, when the engine is stopped, the compressor is operated at a relatively low speed to reduce power consumption, to prevent the engine from starting and thus charging the battery.
According to a tenth aspect of the invention, the target number of revolutions is higher at a high vehicle speed than at a low vehicle speed. In this way, the compressor is operated at a relatively low speed when the automobile drives at a low speed with a little road noise, so that the operation noise of the compressor is less annoying. Meanwhile, the operation noise caused by high speed operation of the compressor is masked by the engine operation noise when the automobile is driven at a high speed with a lot of road noise. Therefore, when the compressor is operated at a relatively high speed, the operation noise of the compressor is less annoying.
In the hybrid vehicle, the possibility of the engine being operated is greater during high speed driving than during low speed driving. Therefore, when there is a high possibility that the engine will be operated, the target number of revolutions can be set to be relatively high, and the same effect as in the ninth aspect can be provided.
According to an eleventh aspect of the invention, the prescribed period can be changed depending upon whether or not the engine is operated.
According to a twelfth aspect of the invention, the prescribed period can be changed based on the vehicle speed.
Incidentally, the parenthesized numerals accompanying the foregoing individual aspects correspond with the embodiments described in the detailed description.